In recent years, surgeons have been increasingly using surgical staples instead of sutures. Surgical staples and surgical stapling instruments have made many difficult procedures much simpler to perform, and significantly reduced the time required to perform them, thus allowing the patient to spend less time under general anesthesia.
In general, modern surgical stapling instruments for use on internal organs and tissues are comprised of a head containing a cartridge which holds the staples and a mechanism for ejecting the staples out of the cartridge, either sequentially or simultaneously, and driving them through the tissue. Typically, on the other side of the tissues to be stapled, there is an anvil, which deforms the staples into the shape required to hold the tissues together. The head and anvil together form the distal stapling portion of the instrument. There is a proximal portion which houses the actuator mechanism for firing the staples, and the mechanism for bringing the anvil and cartridge containing head to the desired distance and keeping them exactly aligned.
A basic consideration in the design of all staplers is the fact that it takes a substantial force to bend the staples. Consequently, at the time the staples are fired, the anvil and the head must be clamped rigidly together, or the force will cause them to separate, and the staples will not fully close. In addition, for the legs of the staples to curl to the shape required to hold the tissues together, the anvil and the staple dispensing part must be aligned precisely. Because of these limitations, in prior art staplers the stapler holding portion and the anvil portion of the device are either rigidly pivotally connected together or, for staplers having separate anvil and staple dispensing parts, the parts of the stapler are manually clamped together when they are at the desired location for stapling.
An improvement over the previously known prior art surgical staplers is disclosed in International Patent Application WO 02/39909 by the same applicant, the description of which, including references cited therein, is incorporated herein by reference. In WO 02/39909 is described a surgical stapler having a totally flexible connection between the anvil and staple dispensing portions of the instrument. In laparoscopic or open operations, such a totally flexible connection will allow stapling in hard-to-reach places. Moreover, such a totally flexible stapling instrument could be combined with a flexible endoscope, which will permit the instrument to be passed through natural orifices, such as the mouth, anus, or vagina. Any number of procedures could then be performed without the need to fully anesthetize the patient, and without opening the abdomen or other organs. A non-exhaustive list includes: removal of broad-based colonic polyps and small cancers; endoscopic treatment of gastresophageal reflux disease (GERD), and full thickness biopsies of gastric lesions. All of which are typically performed under the influence of a general anesthetic.
The invention described in WO 02/39909 is directed towards providing a stapling device for a surgical endoscopic device provided with at least one flexible portion. The stapling device comprises two portions, a cartridge containing a supply of staples and a staple-firing mechanism and an anvil. One of the cartridge portions and one of the anvil portions is located, longitudinally displaced from one another along the longitudinal axis of said endoscopic device, with at least a part of said flexible portion between them.
According to the preferred embodiment of the invention, the flexible section comprises a two-way articulation section, the staple cartridge is located proximately to the proximal end of the articulation section and the anvil is located on the distal tip of the articulation section, and completely bending the articulation section using a fixed radius of curvature brings the two portions of the stapler into alignment.
To hold the two parts of the stapler together during firing, two locking pins or, preferably, screws that are stored in the anvil portion are extended and engage and lock into receptacles on the cartridge.
An ultrasound positioning assembly comprising two separate elements, one of which is located near the cartridge and the other near the anvil, is provided to verify that the parts of the stapling device are correctly positioned relative to each other prior to extending the screws and that there is the correct distance between them before firing the staples. Details of the design and operation of preferred embodiments of the ultrasound positioning system are disclosed in International Patent Application WO 02/068988 by the same applicant, the description of which, including references cited therein, is incorporated herein by reference.
The staple cartridge contains one or a plurality of arrays of staples. Each array consists of one or a plurality of staples. The firing mechanism for firing the arrays of staples comprises staple pushers actuated by cams that are actuated by proximal means. If the cartridge contains more than one array of staples, then an arrangement actuated from the proximal end of the endoscope is provided to index the cartridge after the firing of each of the arrays of staples.
As described in WO 02/39909 and summarized hereinabove, the alignment of the staple cartridge with the anvil is dependent on the design of the articulation section, which has to be capable of bring the two parts of the stapler into exact alignment when it is bent through an angle of 270 degrees. Only if the positioning system verified that the exact alignment had in fact been achieved could the alignment pins or screws be deployed locking the cartridge and anvil together so that the staples could be fired. The alignment accuracy required is about ±1.5 mm. If the articulation section is not able to achieve this degree of accuracy, then when the pins or screws are extended from the anvil they will not enter the matching receptacles in the anvil.
The require degree of accuracy is achievable if expensive manufacturing techniques are used for the production of the individual vertebrae and great care is taken in assembling the entire articulation section. However it has been found by the inventors of the current invention, that even with the most accurate articulation section, difficulties arise in aligning the parts of the stapler. There are two main reasons for these difficulties: firstly, as a result of repeated bending and unbending of the articulation section, wear of the parts takes place resulting in the creation of play between the vertebrae; secondly, when using the device within a body, foreign objects can enter the spaces between the vertebrae, preventing the complete bending of the articulation section.
It is a purpose of the present invention to provide a stapler device comprising a cartridge and an anvil located respectively on the proximal and distal ends of an articulation section in which the shape of the cartridge and the anvil assist in bringing the parts of the stapler into alignment for firing the staples, thus overcoming the difficulties of the prior art.
Further purposes and advantages of this invention will appear as the description proceeds.